Neo4J - JPQL query on @ManyToOne not working

ricardojlrufino · **Joined:** Fri May 08, 2015 1:10 pm **Posts:** 1

Hello, I am trying to make a query (JPQL) in a relationship 'ManyToOne' and I'm a NullPointerException.

And the same can do via Cypher queries (createNativeQuery)

Code:

TypedQuery<DashboardItem> query = em.createQuery("from DashboardItem WHERE parent = :parentID ORDER BY id", DashboardItem.class);
query.setParameter("parentID", dashboard);

Quote:

Exception in thread "main" java.lang.NullPointerException
at org.hibernate.ogm.type.impl.ManyToOneType.getIdGridType(ManyToOneType.java:56)
at org.hibernate.ogm.type.impl.ManyToOneType.nullSafeSet(ManyToOneType.java:64)
at org.hibernate.ogm.datastore.neo4j.Neo4jDialect.getNamedParameterValuesConvertedByGridType(Neo4jDialect.java:621)
at org.hibernate.ogm.datastore.neo4j.Neo4jDialect.executeBackendQuery(Neo4jDialect.java:572)
at org.hibernate.ogm.query.impl.OgmQueryLoader$OgmQueryLoaderContext.executeQuery(OgmQueryLoader.java:150)

Using native queries runs smoothly

Code:

Query query = em.createNativeQuery("MATCH (n:DashboardItem)-[:parent]->(d:Dashboard) where d.id = {dashID} RETURN n ORDER BY n.id", DashboardItem.class);
query.setParameter("dashID", dashboard.getId());

Entities

Code:

@Entity
public class Dashboard {

    @OneToMany(mappedBy = "parent", cascade = CascadeType.ALL, fetch=FetchType.EAGER)
    private Set<DashboardItem> items = new HashSet<DashboardItem>();

}
@Entity
public class DashboardItem {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    @ManyToOne
    private Dashboard parent;
}

What am I doing wrong?

DavideD · **Joined:** Fri Sep 09, 2011 3:18 am **Posts:** 295

Hi,
currently, in OGM, it is not possible to execute queries on associated entities.
This is something we want to improve, in the meanwhile, using a native query is the suggested alternative.

Cheers,
Davide

Gunnar · **Joined:** Sat Jan 24, 2009 12:46 pm **Posts:** 388

Hi,

I have created https://hibernate.atlassian.net/browse/OGM-825 for this. It should be possible to support this query in some cases (if the id is stored on the "current" side of the association), for Neo4j also in general as we can traverse relationships.

--Gunnar